Which potent mu opioid is commonly used as an anesthetic adjunct and may be given as a transdermal patch?

• A. Edrophonium
• B. Fentanyl
• C. Sevoflurane
• D. Oxymorphone

Answer: (B)

Fentanyl is a highly potent mu opioid receptor agonist whose properties make it ideal as an anesthetic adjunct and suitable for a transdermal patch. Its potency—much greater than morphine—provides profound analgesia with small volumes, which helps you achieve strong pain relief during surgery while allowing rapid titration. Its high lipophilicity lets it reach the brain quickly, giving fast onset and offset, which is crucial for adjusting anesthesia as needed. For longer-term pain management, a transdermal fentanyl patch delivers a steady, predictable release over days, offering continuous analgesia without frequent dosing.

Edrophonium is a cholinesterase inhibitor used to diagnose or reverse neuromuscular blockade, not for pain relief. Sevoflurane is an inhaled anesthetic, not an opioid. Oxymorphone is a potent mu opioid, but it isn’t commonly used in a transdermal patch form for ongoing analgesia, and it’s not the standard choice for an anesthetic adjunct in practice.